One does not explain a doctrine and actions engendered by it if one declares that it was generated by the spirit of the age or by the personal or geographical environment of the actors. In resorting to such interpretations one merely stresses the fact that a definite idea was in agreement with other ideas held at the same time and in the same milieu by other people. What is called the spirit of an age, of the members of a collective, or of a certain milieu is precisely the doctrines prevailing among the individuals concerned.

A characteristic feature of present-day popular ideas concerning social cooperation is what Freud has called the belief in the omnipotence of human thought (die Allmacht des Gedankens).8  This belief is, of course, (apart from psychopaths and neurotics) not maintained with regard to the sphere that is investigated by the natural sciences.

The “social engineer” is the reformer who is prepared to “liquidate” all those who do not fit into his plan for the arrangement of human affairs. Yet historians and sometimes even victims whom he puts to death are not averse to finding some extenuating circumstances for his massacres or planned massacres by pointing out that he was ultimately motivated by a noble ambition: he wanted to establish the perfect state of mankind. They assign to him a place in the long line of the designers of utopian schemes.

The self-styled behavioral sciences want to deal scientifically with human behavior.15  They reject as “unscientific” or “rationalistic” the methods of praxeology and economics. On the other hand, they disparage history as tainted with antiquarianism and devoid of any practical use for the improvement of human conditions.

Radical empiricism rejects the idea that certain knowledge concerning the conditions of the universe is accessible to the minds of mortal men. It considers the a priori categories of logic and mathematics as assumptions or conventions, freely chosen on account of their convenience for the attainment of the kind of knowledge that man is able to acquire. All that is inferred by deduction from these a priori categories is merely tautological and does not convey any information about the state of reality.

According to an often quoted dictum of Auguste Comte, the objective of the—natural—sciences is to know in order to predict what will happen in the future. These predictions are, as far as they refer to the effects of human action, conditional. They say: If A, then B. But they do not tell anything about the emergence of A. If a man absorbs potassium cyanide, he will die. But whether he will swallow this poison or not is left undecided.

Many data with which the mind is concerned either in retrospect or in planning for the future can be expressed in numerical terms. Other relevant magnitudes can only be put into words of a nonmathematical language. In regard to such magnitudes the specific understanding of the sciences of human action is a substitute, as it were, for the unfeasibility of measurement.

In forecasting what may or will happen in the future, man can either be right or mistaken. But his anticipation of future events cannot influence the course of nature. Whatever man may expect, nature will go its own way unaffected by any human expectations, desires, wishes, and hopes.

Economics can predict the effects to be expected from resorting to definite measures of economic policies. It can answer the question whether a definite policy is able to attain the ends aimed at and, if the answer is in the negative, what its real effects will be. But, of course, this prediction can be only “qualitative.” It cannot be “quantitative” as there are no constant relations between the factors and effects concerned. The practical value of economics is to be seen in this neatly circumscribed power of predicting the outcome of definite measures.